Hi guys
I have searched and searched for an answer to my problem, I cannot find a correct answer so here is my problem
I have a 93 civic si hb with an itr motor it is a track only car, after switching from my B16a to the itr I found that my regular integra front brakes were not stopping the car, safely. So I upgraded the front brakes to legend twin pot with prelude re drilled rotors and hawk blues, and a 1" m/c with a manual brake booster (the slim one). The rear brakes are stock 93 civic si calipers with hawk hps pads. When I brake really late in a fast corner from 200+km I cannot get the car slowed safely it un weights and spins sending me off the track. the previous regular integra setup allowed me to brake late and not spin.

So my question is should I

a. change the rear brake setup to a rsx/ep3 setup? (or something similar legend)

b. change the prop valve? is an integra prop valve different than a civic? is and itr prop valve different than a reg integra?

c. install a adjustable prop valve? with or without upgrading the rear brake setup?

I hope I have provided enough info.

 

i'm going to bet "too much nose dive"... you might need to bump spring rates.

 

I have 550 front 650 rear 24mm sway bars all aorund

 

i've never seen your car in action or driven it... so i cant offer set up tips but...

if you upgraded your front brakes and now you are "spinning" because your rear is unloaded... you have to "push" the rear tires back down with front spring and possibly minimize dive with more rear braking.

thats my thinking anyway. i've been wrong before

 

Springs are a bit light for a track only car....
Are you at least running a 40/40 prop valve? GSR and above have them.
If not you should be. Too much front bite will cause a spin.

 

That hawk blue is an agressive pad. They are really not forgiving. Maybe try a less aggressive pad.

 

ditch the blues and go ht10 or dtc 60 (nothing to do with your issue).
those rates are way too soft. you should be at least 700 in the front.
try a less agressive pad (parts store basic)

this all hinges on: what tire you are on and how much your car weighs.

 

My spring rates are stiff considering the tracks I run on up here, They are not as smooth as the american tracks.

I am using the stock 93 si hb prop valve, Is it possible to use a gsr or itr prop valve in my car? The reason I ask is both gsr and itr came with abs and my car does not have abs.

I'm guessing there is a difference between eg si hb prop valve and integra gsr prop valve

the car weighs 2292lbs with me in it, and runs on toyo ra-1

I will consider the pad choice aswell

I would like to figure out the difference between the prop valves though.

 

You can use the GSR 40/40 prop valve.

 

are you running the blue pads in the rear as well? usually you want to runa less agressive pad in rear otherwise rear just locks up alot and spins. i run ht10 in front and running regular brake pads in the rear on my hatch. anymore aggressive in the rear and when i get on the brakes they lock and i spin.

 

I feel is way to light in the front on the spring rates to slow down from 200 kph. Isn't that like 125 mph. You have some long straights in there.

 

I always thought too much front brake bite meant you'd never have to worry about spinning the car under the brakes, and that the fronts would just lock up before you'd have to worry about the rears locking. I was always under the impression that spins in a straight line under braking meant that the rears were locking, or too aggressive for the fronts.

Did you 93 Si have discs in the back from the factory? If so, you already have the right prop valve. Some of the 94 and up Integras did not have ABS, so you could use that prop valve if you Civic does not have the right one yet.

 

In my opinion I think you have a compound problem.
Wrong suspension set up, brake pads, check the brake system, You are using R compound tires and trying to brake too late.

Don't know how you drive or experience or how deep you can go. To me is the whole package. Usually if you lock fronts you just go straight off the track. I've been there. straight off the track. Not spinning.

 

With Blues in the front and HPS in the rear, I don't think your rear brake lockup problems are caused by compound issues. The HPS is a minimal upgrade over the stock or parts store pads.

I'd put my money on a bias problem causing the rear lockup and I'll explain why that is once you explain your initial brake problems after the engine change.

But first, let's do some root cause analysis.
You mention the brakes would no longer safely stop the car. Explain your previous issues. Were you experiencing rear wheel brake lockup issues after the engine swap, but before upgrading brake parts? Or were you having brake fade/temperature issues that indicated a brake size upgrade? In short, what problem were you having that necessitated a brake upgrade?

 

Some video of you driving the car before and after the brake change might help too. My hunch is that you have too much front brake bias though. This in turn has extended your braking zones, but you are still starting to brake at the same point. You are going too fast still at the turn in point and you're still on the brakes which results in the car going around on you.

 

I don't have any before and after video footage

with my b16a I had integra front brakes with hawk blues and stock 93 si hb rear brakes with hps pads, I had no braking issues except temp. and brake wear, (pad and rotors)

since switching to the type r swap I felt the integra brakes were not stopping the car safely and I was feeling and seeing that I needed bigger brakes to stop the car. With the legend front calipers and prelude discs and blue pads I have almost no brake wear, and lower temp, but this one fast corner at my local track is catching me out I want to be able to brake later than I am but when I try the rear brakes lock up and cause the car to spin, If I brake earlier and softer no problem.

I am not turning while still braking this problem I'm having happens in the braking zone before corner turn in.

One of the other cars I race with is a 93 da gsr with the same type r swap and the same front brake upgrade although he has not changed his rear brakes does any one know if an integra has a different prop valve than a eg civic si hb? and if so which integra has the correct prop valve without abs?

Or should I invest in a adjustable prop valve.

 

I would put some stock pads on the rear of the car first and see what happens. Unusual for a front brake upgrade to cause the rears to lockup though. That said, I've done it before myself.

 

Just to eliminate it as a potential issue, what condition/how recently replaced are the rear trailing arm bushings? When they get old and cracked they can cause all sorts of delightfully bizarre rear snap issues. I had a similar problem to what you're describing years ago and replacing those only completely solved the issue.

Also, increasing rear braking power without adjusting bias will almost definitely not help anything with rear lockup, and will also almost definitely make it worse. A bias adjuster would be great, if you're willing to take the time to play with it and get it set up right.

It looks like you haven't yet mentioned the current rear compound, which is pretty important in diagnosing all this. You also didn't really answer what braking problems the car had prior to the upgrade. Fade, or just not stopping? Bigger brakes aren't necessarily going to "stop you better" they will really just resist fade more, being a bigger heatsink.

 

this!!!

 

by compound I meant there is more than one problem going on. I was not referring to the tires or the pads. Sorry for the mislead.

Plus I'm with solo-x.

 

Exactly... the behind gets light and around it comes

 

before the brake upgrade the only issue I had was huge pad and rotor wear.

the back stock 93 civic si brakes have hawk hps pads.

after the type r engine swap and legend front brake upgrade the car spins under braking. I am sure that I am not turning the wheel when I am braking the spin happens before the steering wheel is turned.

I am sure that if a change my front brake bias it will help or solve the problem.

so does anyone know what the brake bias is on 93 civic si hb??? or what the % of braking power is front and rear. and the same questions for dc integra also does a type r have a different prop valve agin because of the bigger brakes.

 

One driver I work with has been having a similar issue after upgrading to larger two-piston calipers up front. With him, we've isolated that it is not a driving technique issue as he gets very substantial rear lockup regardless of technique changes and the lockup occurs while braking in a straight line.

Let's simplify an Integra brake system as having a "small" calipers up front and "small" calipers in the rear. ("Small" or "big" being in terms of piston/fluid volume needed to displace the piston) The 4040 prop valve that comes with this system proportions the system properly.

Using a Legend system, you have "big" calipers up front and "big" calipers in the rear. I'm not sure what the prop valve is that is used for this, but whatever proportioning valve is used is sized appropriately for the front and rear caliper sizes.

What I think is happening is that when you mix "big" (2-piston) calipers with "small" rear calipers, you need more fluid to push those front calipers. Imagine that with a stock system you need 5mm of pedal travel to reach maximum braking capability at both ends of the car. Being that there's only one brake pedal and one master cylinder in the car, the front and rear brakes are tied together. Whatever input you give one end, also affects the other. With the bigger front caliper, you might need to get 10mm of pedal travel to push those calipers to achieve maximum braking at the front end BUT now the rear end is getting 10mm of pedal, and that's overloading the rears.

This is somewhat complicated by the fact that the stock proportioning valve ties the brakes together diagonally, that is the LF is tied to the RR and the RF is tied to the LR brake. So you can't just slap an aftermarket prop valve in one line and call it done.

What I suggested as a solution for my driver with this issue:
1- Replumb the brake lines so the front brakes are on one circuit, and the rear brakes are on another.
2- Install proportioning valve on rear circuit
3- Adjust prop valve to quell rear lockup issue

 

WRXRacer is exactly right. That is your problem.

My suggested solution is a little different and much simpler, easier and cheaper and will net you fantastic brakes. Install the single pot brake caliper from the Legend and I think your brake bias issue is done. And yes, your spring rates are much too low. Sorry your track is that shitty, but that does not change the fact that the spring rates are too low for what you are asking your car to do.

I use Legend single pot calipers, re-drilled Prelude rotors on front, stock prop valve and OEM Si caliper/rotor with Porterfield pads. I would never recommend Hawk pads to anyone. If you are looking for a secret weapon for brake pads, look into Carbotech XP10 on the front, the rears you can go with most anything.
The EK coupe that is my track only car has fantastic brakes. 2250 lbs. Tires are RA-1.

 

Absolutely spot on,plus change your spring rates around as I think the ratio from front to rear should be reversed.
We had the same problem with spinning but not a brake fault and now run 700 front and 500 rears and have to stop from over 200 kph every lap and its brilliant and also 1 1/2 seconds a lap faster.Now that that problem is fixed we will be going up in spring rates.
We already have a prop valve on the rear circuit as described.